In a variety of industrial processes, there are areas that are inaccessible and yet at the same time critical to the process. For example, pipes which conduct the flow of process fluids are often embedded in concrete or a similar material such that inspection of critical pipe joints is impossible. If a faulty weld exists or if a critical area should otherwise fail while the pipes are in service, the lack of ability to carry out inspections creates a situation where no warning is given of a possibly dangerous condition. As an example, in a nuclear power plant or other critical facility, if piping which conducts cooling fluid should leak, disastrous consequences can follow. If the piping is capable of being inspected on a regular basis, the problem can be detected early enough to allow corrective action to be taken before there is a complete failure.
Similar situations arise as to pipes and fittings that are submerged in storage tanks for petroleum based liquids and other types of liquids. Access to submerged areas is restricted if not precluded altogether, so leaks and other problems can arise without any warning because inspections of the submerged areas are not practical and perhaps not even possible. The same problems are presented as to inspections in hostile environments such as areas exposed to the high levels of radiation or toxic chemicals.